1. Field of the Invention
The present invention relates to an automatic pump, and particularly to an improved automatic pump capable of advantageously reducing manufacturing processes thereof as well as significantly preventing pressure decrease in a pump assembly by providing a pressure control tube and obviating a sealing process thereof.
2. Description of the Conventional Art
FIGS. 1A and 1B show a construction of a conventional automatic pump, which includes a motor 1 for transmitting driving force to corresponding elements thereof, an impeller 3 cooperatively working with and affixed to a rotary shaft 2 of the motor 1, a working chamber 4 sufficiently formed in front of the motor 1, and a pump casing 5 attached to a predetermined portion of the working chamber 4.
The pump casing 5, as shown in FIG. 2, includes an intake tube 7 disposed in the working chamber 4 and projecting from the front portion of the pump casing 5, an intermediate wall 9 disposed between the working chamber 4 and the pump casing 5 and at a predetermined portions of which a plurality of pressure control openings 8 are provided, an air pressuring port 10 formed on a predetermined portion of the front surface of the pump casing 5, and a rubber blade 12 for encasing a predetermined portion of the pump casing 5 spaced apart from the internal wall 1 la of the pump casing 5. In addition, reference numeral 11 denotes a pressure tank, which is provided between the internal wall 11a of the pump casing 5 and the rubber blade 12.
Meanwhile, an exhausting tube 6 is disposed at a predetermined portion of the upper side of the working chamber 4 for exhausting water flowed from the intake tube 7 through the working chamber 4 to the outside thereof.
As described above, the conventional automatic pump lets water flow into the working chamber 4 through the intake tube 7 as the impeller 3 rotates by receiving driving force from the motor 1. At this time, the water pressured at the working chamber 4 flows toward the outside through the exhausting tube 6. Here, the residual water in the working chamber 4 flows into the pump casing 5, as shown in FIG. 3, thereby disadvantageously decreasing the usable space of the pressure tank 11. That is, the rubber blade 12 is pressured due to the increasing pressure in the pump casing 5.
Meanwhile, in the conventional automatic pump, for example, in case that the automatic pump is stopped, the exhausting pressure therein becomes unstable, so that the pressured air in the pressure tank 11 formed between the pump casing 5 and the rubber blade 12, as shown in FIG. 4, presses against the rubber blade 12. That is, when the pressure against the rubber blade 12 is removed, the pressure tank 11 returns back to its original state, whereby the water in the pump casing 5 flows toward the exhausting tube 6 through the pressure control openings 8 by means of the pressure of the rubber blade 12, which is indicated by the arrows in the pressure tank 11 shown in FIG. 4.
However, although the A- and B-portions formed between the rubber blade 12 and the pump casing 5 shown in FIG. 2 are sealed for preventing the leakage of water therethrough, the leakage performance may not be achieved due to the leakage of pressure therein when the pressure in the pump casing 5 increases. In addition to that, the assembling process may become complicated due to an additional sealing process. In addition, the conventional automatic pump has restrictions to alternatively dispose the rubble 12 and the sealing portions A and B shown in FIG. 2, whereby more compact size may not be achieved thereby.